Another factor in determining which interface option to use is deciding whether the Android platform or the peripheral will provide the USB power. Per the USB specification, the USB host is required to provide the power to the downstream peripheral. It is important to keep in mind that even though the Android platform may provide USB host support, most Android devices are portable requiring battery power to operate. Utilizing the USB client port on the Android platform eliminates the requirement for the Android platform to provide power along with the complex USB host connection and software stack. This results in reducing battery size and cost on the Android platform. The Android platform OS version also plays a role in determining which interface option to use, as Android Open Accessories requires OS version 3.1 onward and the Java driver interface option requires Android OS version 3.2 onward.